Key Publications

Key Journals - The Astrophysical Journal (ApJ), ApJ LETTERS, Monthly Notices of Royal Astronomical Society (MNRAS), MNRAS LETTERS, Nuclear Instrumentations and physics research A, Journal of Astronomy & Astrophysics (JAA), Nature Astronomy

Switch in physics at different timescale in Active galaxies

April 2020

Using a sophisticated Monte Carlo simulation-based cross-correlation technique on month-long X-ray light curve from RXTE/PCA and 1.5 month-long UV continuum light curves from IUE spectra in 1220-1970 Å, we found a remarkable switch from the slow comptonisation delay to the fast X-ray reprocessing delay between UV and X-rays.

measuring spin of a black hole

November 2018

Using X-ray spectral and timing analysis of the transient black hole X-ray binary 4U 1630-47, observed with the AstroSat, Chandra, and MAXI space missions during its soft X-ray outburst in 2016, we determine the dimensionless black hole spin parameter at 0.92 ± 0.04 within the 99.7% confidence interval. Such a measurement implies the central black hole is rotating close to its theoretical maximum limit.

Catching the moment of Radio jet ejection

January 2018

Using a 2-day long X-ray monitoring with AstroSat and Radio monitoring with RATAN, we catch the rare moment when the relativistic radio jet base formed and ejected from the X-ray binary system known as Cyg X-3. Within a hour, the radio flux increases by a factor of ~5 and a very flat and strong Sychrotron emission appeared in the hard X-rays. Such a discovery provides first direct evidence of hard X-ray emission from the radio jet base.